We conducted following tests on a Linux machine (Ubuntu 11.10) with IPv6 disabled. The wireshark capture of those tests are attached.

Test 1: (file: Test1.pcap)
Used libcurl to send HTTP request and did not set CURL_IPRESOLVE_V4 option.
Results: Two DNS requests sent out; one for IPv6 and one for IPv4

Test 2: (file: Test2.pcap)
Used libcurl to send HTTP request and did set CURL_IPRESOLVE_V4 option.
Results: Two DNS requests sent out; both for IPv4

Test 3: (file: Test3.pcap)
Did not use libcurl, instead used a sample program to call getaddressinfo “C” function
set addrinfo.ai_family = AF_INET
Results: Two DNS requests sent out; both for IPv4

Test 4: (file: Test4.pcap)
Did not use libcurl, instead used a sample program to call getaddressinfo “C” function
set addrinfo.ai_family = AF_INET6
Results: Two DNS requests sent out; both for IPv6

Test 5: (file: Test5.pcap)
Did not use libcurl, instead used a sample program to call getaddressinfo “C” function
set addrinfo.ai_family = PF_UNSPEC
Results: Two DNS requests sent out; one for IPv6 and one for IPv4

Looking at the results it appears that when libcurl is used with no IP option set (default being CURL_IPRESOLVE_WHATEVER), it is using “getaddressinfo” with addrinfo.ai_family = PF_UNSPEC. However, when CURL_IPRESOLVE_V4 option is set it is using “getaddressinfo” with addrinfo.ai_family = AF_INET.

Attachment: Test1.pcap (1.1 kB; application/octet-stream) Test2.pcap (1.3 kB; application/octet-stream) Test3.pcap (1.3 kB; application/octet-stream) Test4.pcap (786 Bytes; application/octet-stream) Test5.pcap (1.1 kB; application/octet-stream)

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** [bugs:#1274] IPv6 DNS requests were sent out from Android Handsets even if the IPv6 stack is not present on the device.**
**Status:** open
**Labels:** Android-IPv6 Issue 
**Created:** Tue Sep 03, 2013 09:36 PM UTC by Rajiv Dwivedi
**Last Updated:** Tue Sep 03, 2013 09:51 PM UTC
**Owner:** Daniel Stenberg
Observation:

IPv6 DNS requests were sent out from Android Handsets even if the IPv6 stack is not present on the device.


Expected Result:
If there is no IPv6 stack on the device/machine, the IPv6 request should not be sent from the device.

Workaround:
Using option "CURL_IPRESOLVE_V4", disables sending IPv6 DNS queries.
Libcurl details:
OS: Linux - Android
version: 7.32.0
link: http://curl.haxx.se/download.html


Attachments:
Wireshark log ( which displays both Ipv$ and IPv6 records)
Verbose output using libcurl (captured while making HTTP requests)
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